Migrate to Artifact Registry

Google Container Registry has been recommending migrating to Artifact Registry for some time now.

https://cloud.google.com/artifact-registry/docs/transition/transition-from-gcr

In theory, this should be straight forward:
- Ensure all service accounts have been granted Artifact Registry roles
- One major change is that repositories need to be created.
- Authentication methods are still the same.

`gcr.io` will be replaced by `us-docker.pkg.dev`

https://github.com/knative/test-infra/pull/3004 introduces the new repository in to the Prow build images.

Start by locating the service-account permissions, container image references, and repository configuration affected by the gcr.io to us-docker.pkg.dev migration. Review the Artifact Registry transition guide and knative/test-infra#3004. Done means required repositories and roles are configured and the affected build images no longer depend on the old registry.

Written by the indexing model from the issue text.